1. Field of the Invention
The present invention relates to crystalline superfine particles, complex material, method of manufacturing crystalline superfine particles, inverted micelles, inverted micelles enveloping precursor superfine particles, inverted micelles enveloping crystalline superfine particles and precursor superfine particles that are suitable for use in manufacture of a complex material used in, for example, the field of entertainment, the field of amusement or the field of optics.
2. Description of the Related Art
For years, aluminate compound materials doped with rare earth elements have been remarked as fluorescent materials, and have been under vigorous researches. Among various aluminate compound materials, Eu-doped SrAl2O4 (written as SrAl2O4:Eu herein below) has attracted the greatest attention as from a report on the phenomenon of stress emission as introduced later. Thus, prehistory of researches and developments of this SrAl2O4:Eu is first explained below while citing prior art documents.
History of Patents and Researches of SrAl2O4:Eu as Fluorescent Material
SrAl2O4:Eu has the prehistory of having been studied as a fluorescent material from a long time ago. U.S. Pat. No. 3,294,699 on this material issued already in the 1960s, and the material is currently one of known materials.
History of Inventions and Researches of Phosphorescent Material/Long-afterglow Phosphor SrAl2O4:Eu+Dy (Under the Brand of “LumiNova”) by Nemoto & Co., Ltd.
There are many reports and commentaries on this phosphor, some of which are listed below.
Non-Patent Document 1:
    URL: http://www.nemoto.co.jp/index_j.html accessed through the Internet on Aug. 30, 2002Non-Patent Document 2:    URL: http://www.nemoto.co.jp/products/luminova/index.html accessed through the Internet on Aug. 30, 2002Non-Patent Document 3:    URL: http://www.nemoto.co.jp/product/01_luminova/index.html accessed through the Internet on Aug. 30, 2002Non-Patent Document 4:    URL: http://www.nemoto.co.jp/column/10_glow.html accessed through the Internet on Aug. 30, 2002Patent Document 2:    Specification of Japanese Patent No. 2543825Patent Document 3:    Specification of U.S. Pat. No. 5,424,006Patent Document 4:    Specification of European Patent No. 622440Non-patent Document 5:    T. Matsuzawa, N. Takeuchi, Y. Aoki and Y. Murakami, 248th Lecture Papers of Phosphor Research Society “Proc. Phosphor Res. Soc.” (1993.11.26) 7–13Non-patent Document 6:    Yoshihiko Murakami, Nikkei Science, 5(1996) 20–29Non-patent Document 7:    T. Matsuzawa, Y. Aoki, T. Takeuchi and Y. Murayama, J. Electrochem. Soc., 143(1996) 2670–2673Non-patent Document 8:    Y. Murakami, Ceramics, 32(1997) 40–43Non-patent Document 9:    Y. Murakami, Hakaru, 42(1997) 2–7Discovery of stress emission in SrAl2O4:Eu compound materials by C-N. Xu, et al. of National Institute of Advanced Industrial Science and Technology (AIST), Institute for Structural and Engineering Materials (ISEM), Multifunctional Materials Technology Group (former, MITI Institute for Industrial Technology, Kyushu Institute for Industry and Technology, Laboratory for Inorganic Complex Materials and Functional Ceramics) as well as history of related patents and researches
There are many commentaries and reports on the stress emission SrAl2O4:Eu compound materials and related substances, such as, for example, Non-patent Documents 10–17 and Patent Documents 5–19 that are listed below.
Non-patent Document 10: C-N. Xu, AIST Today, vol. 2, No. 8 (2002)
Non-patent Document 11:
    URL: http//www.aist.go.jp/aist_j/aistinfo/aist_today/vol02—08/vol02—80_main.html accessed through the Internet on Aug. 30, 2002Non-patent Document 12:    URL: http//www.aist.go.jp/aist_j/aistinfo/aist_today/vol02—08/vol02—08_p13.pdf accessed through the Internet on Aug. 30, 2002Non-patent Document 13: C-N. Xu, T. Watanabe, M. Akiyama and X-G. Zheng, Appl. Phys. Lett., 74(1999) 1236–1238Non-patent Document 14: C-N. Xu, T. Watanabe, M. Akiyama and X-G. Zheng, Appl. Phys. Lett., 74(1999) 2414–2416Non-patent Document 15: C-N. Xu, X-G Zheng, M. Akiyama, K. Nonaka and T. Watanabe, Appl. Phys. Lett., 76(2000) 179–181Non-patent Document 16: C-N. Xu, Kagaku Kogyo (October 2000) pp. 790–794 & 808Non-patent Document 17: C-N. Xu, Gekkan Display, September (2001) 98–103Patent Document 5: Japanese Laid-open Publication JP-H11-116946-APatent Document 6: Specification of Japanese Patent No. 3265356Patent Document 7: Specification of Japanese Patent No. 3136340Patent Document 8: Specification of Japanese Patent No. 3136338Patent Document 9: Specification of Japanese Patent No. 2992631Patent Document 10: Japanese Patent Laid-open Publication JP-2000-313878-APatent Document 11: Japanese Patent Laid-open Publication JP-2001-49251-APatent Document 12: Japanese Patent Laid-open Publication JP-2001-123162-APatent Document 13: Japanese Patent Laid-open Publication JP-2001-215157-APatent Document 14: Specification of Japanese Patent No. 3273317Patent Document 15: Japanese Patent Laid-open Publication JP-2002-194349-APatent Document 16: Japanese Patent Laid-open Publication JP-2002-194350-APatent Document 17: Japanese Patent Laid-open Publication JP-2002-201068-APatent Document 18: Specification of U.S. Pat. No. 6,117,574Patent Document 19: Specification of U.S. Pat. No. 6,159,394
Patent Document 5 discloses materials that contain 0.01˜20 weight percent of rare earths or transition metals and emit light with external mechanical energy received by a wurtzite type piezoelectric material. Patent Document 6 discloses thin films of these materials. Patent Document 7 discloses materials that contain transition elements or rare earth elements having electron shells of 3d, 4d, 5d and 4f added to MgAl2O4, CaAl2O4, Al2O3 and SrMgAl10O17 as their matrices and emit light upon deformation with a mechanical external force, as well as a manufacturing method thereof. Patent Document 8 discloses materials that are made of substances containing transition elements or rare earth elements having electron shells of 3d, 4d, 5d and 4f as emission center ions and added to matrix crystals of metal oxides/complex oxides, and emit light by mechanical deformation. Patent Document 9 discloses materials containing transition elements or rare earths added to matrix materials of Sr3Al2O6 and Ga3Al2O6, as well as a manufacturing method thereof by baking under a controlled amount of the additive substance in 0.01˜20 weight percent in a reducing atmosphere adjusted to 800˜1700° C. Patent Document 10 discloses materials containing rare earths or transition metal elements as emission centers added to matrix materials of Y—Ba—Mg—Si oxides, which convert external mechanical energy to light. Document 11 describes materials that contain regulated aluminate having a non-stoichiometrical composition and emit light under mechanical energy. Document 12 describes mMO.nAl2O3 materials as phosphorus memory excited by visible light. Patent Document 13 discloses a system for measuring the stress profile by using a stress emission material. Patent Document 14 discloses materials that contain oxides having a melilite type crystal structure (such as CaYAl3O7, Ca2Al2SiO7 or the like) as their matrices and emit light under mechanical energy. Patent Document 15 discloses materials MN2O4, where M═Mg, Sr, Ba or Zn, N═Ga or Al, doped with rare earths or transition metals as their emission centers, together with a manufacturing method thereof. Patent Document 16 describes field emission materials composed of aluminate as their matrices and doped rare earths or transition elements. Patent Document 17 discloses electrostriction materials of (Sr, Ba, Mg, Ca, Zn, Cd)-(Al, Ga, Si) oxides having the maximum distortion of 1%. This is a considerably large value. Patent Document 18 discloses piezoelectric materials as triboluminescent materials. Document 19 mainly describes Sr3Al3O6 as stress emission materials, and this document corresponds to Patent Document 9.
Next explained are prior art technologies for complexing stress emission substances, mainly SrAl2O4-based fine particles, with resins.
Products incorporating complex materials commercially named “LumiNova” (SrAl2O4:Eu+Dy) into resins are on sale in form of “incorporated resin pellets” from Nemoto & Co., Ltd. They are introduced in the web sites, URL: http://www.nemoto.co.jp/products/luminova/index.html accessed through the Internet on Aug. 30, 2002 and herein taken as Non-patent Document 18, and URL: http://www.nemoto.co.jp/products/gss/index.html accessed through the Internet on Aug. 30, 2002 and herein taken as Non-patent Document 19.
The above web documents and Non-patent Document 9 disclose polymethylmethacrylate (PMMA), ABS resins, polycarbonate (PC), polystyrene (PS), Polyethylene (PE), polypropylene (PP), polyacetals (PA) and urethane resins as resin materials. Further, according to the web documents, there seems to be a trial of incorporation into silicone rubber. However, no details are disclosed. About mixture ratios of powder and resins, a ratio around 10% in weight percent is the sole suggestion.
On the other hand, most of complex materials reported in research papers of the discoverer of stress emission, Xu, and others, are mixtures of powder into epoxy resins as matrices, and they are in form of bulk aggregates. Therefore, strong mechanical force from a vise, for example, is required to induce their emission of light.
In Non-patent Document 10, Xu describes application of his complex materials mainly to technologies for visualizing stress profiles and various types of displays. However, he describes or suggests nothing about development of their applications to artificial light-emitting skins, artificial light-emitting hair, artificial light-emitting bodies, artificial light-emitting cloth, and like others, for the purpose of entertainment. Additionally, in relation to complexing techniques, the sole statement is found in a research paper about epoxy resin molding. Complexing with other resins is not found at all in the web documents either.
Some products as applications of phosphorescent materials developed by Nemoto & Co., Ltd. are distributed from Tokyo Intelligent Network Kabushiki Kaisha (Non-patent Document 20: URL: http://www2.raidway.ne.jp/˜tin/ accessed through the Internet on Aug. 30, 2002, and Non-patent Document 21: URL: http://www2.raidway.ne.jp/˜tin/nl/nl.html accessed through the Internet on Aug. 30, 2002), and products from San Unit Company (Non-patent Document 22: URL: http://web.kyoto-inet.or.jp/people/sansanuc/s4/html accessed through the Internet on Aug. 30, 2002). Products of Non-patent Documents 20, 21 are applications to phosphorescent tiles, phosphorescent straps, phosphorescent special make gels, phosphorescent wallpaper, and so on, as applications of phosphorescent materials. Products of Non-patent Document 22 are applications of phosphorescent materials to tiles, paints, pellets, balls, and so on. However, there is no disclosure or suggestion on developments of applications to artificial light-emitting skins, artificial light-emitting hair, artificial light-emitting bodies, artificial light-emitting cloth, and like others, for the purpose of entertainment.
There are documents concerning transparent phosphorescent materials although none of them discuss stress emission. Patent Document 20 (JP-H06-43580-B) discloses highly transparent fluorescent films extremely reduced in voids in the fluorescent films. Patent Document 21 (JP-H07-195890-A) describes fluorescent writing/drawing instruments containing transparent fluorescent inks and having ultraviolet lamps, and explains that images drawn with the instruments can be changed visible and invisible repeatedly. Patent Document 22 (JP-H09-95671-A) describes that transparent phosphorescent materials are obtained by using ultrafine particles of a grain size not reflecting visible light (1 to 100 nm) as the phosphorescent phosphors and complexing them with transparent binders, and this document discloses SrAl2O4:Eu phosphorescent phosphors as their embodiments. Patent Document 23 (JP-H06-227192-A) discloses commuter tickets using transparent phosphorescent inks or transparent infrared absorption inks and effective for preventing falsification. Patent Document 24 (JP-H09-183288-A) discloses a sheet having secret information of characters or others written by transparent ink to prevent falsification. These documents relate to materials essentially different in function from stress emission materials.
There is a proposal of a method for synthesizing ultrafine particles by using inverted micelles (Non-patent Document 23: T. Kawai, Shokuzai, 71(1993) 449).
Furthermore, it has been reported that ultrafine particles can be aligned in order by using exchange reaction of ligands on surfaces of ultrafine particles (Non-patent Document 24: T. Torimoto and F. Ohtani, Electrochemistry, 69(2001) 866). As an example of surface modification by ligand exchange of organic molecules covering precursor ultrafine particles with desired organic molecules, it has been proposed to coat the surfaces with molecules such as polyoxyethylene (1) lauryl ether phosphoric acid or polyoxyetylene (4, 5) lauryl ether (Patent Document 25: Japanese Patent Laid-open Publication JP-2002-20471-A).
In any of the above-introduced prior art techniques, stress emission particles are prepared by crushing ceramics prepared by solid phase reaction into powder.
Therefore, it was difficult to obtain stress emission particles of a uniform grain size, and the grain size was as large as several μm. Accordingly, it has been difficult to obtain complex materials in which stress emission particles are uniformly dispersed. Moreover, it was difficult to apply stress emission particles to devices having micro-sized structures. For example, in case of preparing stress emission artificial hair by packing stress emission particles in transparent tubes, a limit of downsizing the diameter of the tubes will make it difficult to obtain sufficiently thin stress emission artificial hair.
Furthermore, since stress emission particles having a grain size as large as several μm scatter and reflect light in the range of visible light (wavelengths from 400 to 750 nm), it was impossible to prepare transparent stress emission materials from those stress emission particles. Therefore, the conventional stress emission particles are not suitable for use in portions such as a display panel required to be transparent, with which it is necessary to confirm information on one surface of the panel from the opposite surface through the panel.